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Witnesse UNITED STATns N JAMES A. LAWSON, OF TROY, NEW YORK.

.PATENT OFFICE.

IMPROVEMENT IN HOT-AIR FURNACES.

Speciiication forming part of Letters Patent No. 116,724, dated July 4, 1871.

.To all 'whom it may concern:

Beit known th atl, J AMEsA. LAwsoN, of Troy, in the county of Rensselaer' and in'the State of New York, have invented certain new and useful Improvements in Hot-Air Furnaces and do hereby declare that the following is a full, clear, and exact description thereof', reference bein g had to the accompanying drawing makin g a part of this specification, in which-L y Figure 1 is a perspectiveview of my improved furnace. Fig. 2 is a plan View of the upper side of the same. Fig. is a horizontal section on the line .fr .c of Figs. and 3. Fig. 4 is a vertical central section from front to rear. `Figf is a vertical central section of the upper portionof said furnace as arranged for a low room. Fig. 6 is a perspective view of the combined exit and side fines. Fig. 7 is a vertical section of the sa-me on'the line x a ot' Fig. (i. Figs, 8, 9, 1 0, and ll are vertical central `sections `of different forms or niodijications of the side fines 5 and Figs. 12 and 13 are vertical central sections of the upper section of the furnace, showing modifications in the form and arrangement of the side iiues and dome.

Letters of like name and kind refer to like parts in each of the gures.

My invention is an improvement upon awoodburning heating-furnace for which Letters Patent No. 70,445 were granted me, November 5, 1867; and it consists, principally, in the peculiarI form of the the vertical or side iiues, substantially as and for the purpose hereinafter shown. It further consists in the employment of a diving exitilue and a vertical side iue combined, substantially as and for the purpose set forth. It further consists in the peculiar construction of the additional or special-side nues, substantially as and for the purpose hereinafter shown and described. It finally consists ,in the general coin struct-ion and relative arrangement of its parts, whereby said furnace is adapted to the use of coal, substantially as is hereinafter specified.

In the annexed drawing, `A represents the ash.. pit, inclosed at its front side by means of a door, B, containing a draught-damlier, O, and surmounted by a fire-pot, D, provided with a feedchute, E, all of usual construction. The cover F ot the combustion-chamber extends upward for a short distance from the fire-pot in nearly a vertical line 5 from thence extends horizontally inward sufficiently to `give a bearing for the side pipes, and from thence curves upward and inward so as to forni a ""ound-top dome, F. Exten'din g vertically upward from equidistant points around the horizontal iortion of the cover F is a series of pipes or si( e fines, G, having a general tiiangulartbrm, vertically, the lower open `.ends of whichare placed over corresponding openings .f provided in and through said cover, and within suitable inclosing packing-anges f that extend vertically upward from the same. Resting upon the upper ends of ilues G is an annular tine, H, provided with openings lL and pacling-flanges h', for the reception of the end of each flue, which openin gs and tlan ges correspond there with, andare similar to those provided for the lower ends of said pipes. In order that the space between theside. fines Gr may not be materially less at their inner than at their outer edges, their sides are formed upon horizontally-radial lilies, so as to give to said fines a wedge-shape., as seen in Fig. 3. A straight pipe or flue, I, extending from side to side across the center of the annular iiue H, and provided at its center with an opening, K, through which the hea-ted escaping products'of combustion pass from the heater to the chimney, completes'thedevice, the operation of which is as follows:

The heated gases passing upward from the burning fuel are drawn to the outer side of the `combustion-chaniber and into the open ends of the side pipes,- froln whence, dividing, said currentspass upward in diverging lines to the vertical centers ot"V said pipes, where, iinpin ging against the `converging sides of the same, their course is changed so as to cause them to unite at the upper ends of said tlues, after leaving which said gases pass through the annular ilue, thencentral arm, and the exit-flue into the chimney. The peculiar shape of the side lues gives to them the largest possible radiating surface, and as, from theirrelative arrangement, the eX- `ternal air has free access to every portion of the same, so large a percentage of the heat of the vescaping productsoi' combustion is withdrawn therefrom and communicated to the smrounding air that the temperature of said escaping gases upon entering the chimney is sufficient only to give to the air contained therein the nccessar f upward motion to insure a perfect draught. As hereinbefore shown, the exit-flue K extends upward from the cross-Hue I; but, as the limited space within a furnace-room frequently renders such an arrangement impracticable, it has been. found necessary to provide a similar opening, K, within the lower side of said rlue I, and connect therewith a pipe, L, tha-t from thence extends in a curve downward and radially outward, and enters the chimney at or near the upper end of the furnace. From its size it would be imprac ticable for the pipe L to pass between two of the side pipes G, or to occupy the space allotted to one of the same, while if two of said pipes were omitted the radiation of heat from that point would be lessened, and a space left within the annular' flue I-I upon which ashes would lodge so as to obstruct the draught. To obviate these objections, it has been found advantageous to combine one of said side lues (without its central opening) with said pipe L, as seen in Fig. 5, and to place upon either side ofthe same single tlues G', constructed without the usual inner angular branch, by which arrangement the uniformity of exterior appearance and of radiating surface is preserved, and the free circulation of air around and between said parts is unimpeded. From its peculiar angular shape the diamond iiue is believed to utilize a larger percentage of the heat ofthe escaping products of combustion than though said angles were omitted and curved lines substituted, (as shown in Fig. 8,) as the diverging currents of gas, when suddenly caused to converge, impinge with considerable force against the outer wall ofthe flue, and impart to the same a higher temperature than would otherwise beattainable; but it will be readily seen that the principle of operation would be the same with each form, the only difference being that of degree. If desired, the expense ofthe side iiues may be materially decreased by omitting the cen.- tral opening for external air, and inserting a horizontal diaphragm, g', (as shown in' Fig. 10,) so as to divide the current of heated gases, or (as seen in Fig. 11) a like result couldbe obtained by the employment of a A -shaped diaphragm, g, but, while in either case the cost of constructing said tlues would be considerably reduced, it is befines are self-cleaning, or rather are so formed asV to prevent ashes from lodging therein, but cause the same to fall downward into the tire-pot, by which means but slight attention is required in the operation of said furnace, and its heating capacity is unimpaired by use.

Having thus fully set forth the nature and merits of my invention, what I claim as new isl. The side iiues G, provided with diverging and converging passages, and having their vertical sides formed upon lines diverging horizontally from a common center, so as to give to said ues a general wedge-shape in plan view, substantially as and for the purpose specified.

2. The exit-line L and side iiue G, when conr bined in the manner and for the purpose substantially as shown and described.

3. The single side ilues G, substantially as and for the purpose set forth.

4. The side iiue G, provided with the diaphragm g or g, substal'itially as and for. the purpose shown.

5. The general construction and relative arrangement of the lire-pot D, the dome F, the side pipes G, and the annular ilue H, substantially as and for the purpose specified.

1n testimony that I claim the ioregoing Ihave hereunto set my hand this 1st day of June, 1871.

JAS. A. LAWSON.

Vv'itnesses Gno. A. WnLLs, GHAs. H. HAZARD. 

